CVE-2026-63868

Summary

In the Linux kernel, the following vulnerability has been resolved: net: garp: fix unsigned integer underflow in garp_pdu_parse_attr The receive-side GARP attribute parser computes dlen with reversed operands: dlen = sizeof(*ga) - ga->len; ga->len is the on-wire attribute length and includes the GARP attribute header. For normal attributes with data, ga->len is larger than sizeof(*ga), so the subtraction underflows in unsigned arithmetic. The resulting value is later passed to garp_attr_lookup(), whose length argument is u8. After truncation, the parsed data length usually no longer matches the length stored for locally registered attributes, so received Join/Leave events are ignored. This breaks the GARP receive path for common attributes, such as GVRP VLAN registration attributes. Compute the data length as the attribute length minus the header length.

Impact & exploitability

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products we track (1)

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/04e22fefac1af3e32f245e9045382348773b5d59 ↗

Additional information

• NVD record
• https://git.kernel.org/stable/c/04e22fefac1af3e32f245e9045382348773b5d59Patch
• https://git.kernel.org/stable/c/16e408e607a94b646fb14a2a98422c6877ae4b3cPatch
• https://git.kernel.org/stable/c/29f28172afb2ae7b31e9bf3e978396f20b381688Patch
• https://git.kernel.org/stable/c/74e02121be1dcc0efcd56ebdf0171d6129105659Patch
• https://git.kernel.org/stable/c/973cf7c433d27f4d9556d0b7c332543be7ed7a6ePatch
• https://git.kernel.org/stable/c/a11f1a671b1361f0f1278dc0041374f2730df73fPatch
• https://git.kernel.org/stable/c/d4c86ea09ae3e63ee5aa86e941fcc38e0e39874aPatch
• https://git.kernel.org/stable/c/d8dcd14aa886b8effd83022c550669f4f262854bPatch